2013 Boston Marathon bombing survivor Erika Brannock, a pre-school teacher from the Baltimore area, and her mother, Carol Downing, at right, walk across the Marathon finish line after a remembrance ceremony on Boylston Street in Boston, Tuesday, April 15, 2014. (AP Photo/Elise Amendola) ORG XMIT: MAEA109 less

2013 Boston Marathon bombing survivor Erika Brannock, a pre-school teacher from the Baltimore area, and her mother, Carol Downing, at right, walk across the Marathon finish line after a remembrance ceremony on ... more

Olivia Savarino, center, hugs Christelle Pierre-Louis, left, as Callie Benjamin, right, looks on near the finish line of the Boston Marathon during ceremonies on Boylston Street, Tuesday, April 15, 2014, in Boston. Savarino and Benjamin were working at the Forum restaurant when a bomb went off in front of the building on April 15, 2013. (AP Photo/Steven Senne) ORG XMIT: MASR106 less

Olivia Savarino, center, hugs Christelle Pierre-Louis, left, as Callie Benjamin, right, looks on near the finish line of the Boston Marathon during ceremonies on Boylston Street, Tuesday, April 15, 2014, in ... more

Survivors, officials, first responders and guests pause as the flag is raised at the finish line during a tribute in honor of the one year anniversary of the Boston Marathon bombings, Tuesday, April 15, 2014 in Boston. (AP Photo/Charles Krupa) ORG XMIT: MACK104 less

Survivors, officials, first responders and guests pause as the flag is raised at the finish line during a tribute in honor of the one year anniversary of the Boston Marathon bombings, Tuesday, April 15, 2014 in ... more

Photo: Charles Krupa

Survivors, officials, first responders and guests pause as the flag... Photo-6171541.83992 - Times Union

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Survivors, officials, first responders and guests pause as the flag is raised at the finish line during a tribute in honor of the one year anniversary of the Boston Marathon bombings, Tuesday, April 15, 2014 in Boston. (AP Photo/Charles Krupa) ORG XMIT: MACK103 less

Survivors, officials, first responders and guests pause as the flag is raised at the finish line during a tribute in honor of the one year anniversary of the Boston Marathon bombings, Tuesday, April 15, 2014 in ... more

Photo: Charles Krupa

Survivors, officials, first responders and guests pause as the flag... Photo-6171542.83992 - Times Union

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Taboola Gallery Frame Item-85307.83992 - Times Union

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Heather McDade of Boston, center, reacts while watching a tribute ceremony with others on an over-sized outdoor monitor, Tuesday, April 15, 2014, on Boylston Street in Boston. The ceremony was held for those killed and injured in the bombings at the finish line of the Boston Marathon a year ago. (AP Photo/Steven Senne) ORG XMIT: MASR102 less

Heather McDade of Boston, center, reacts while watching a tribute ceremony with others on an over-sized outdoor monitor, Tuesday, April 15, 2014, on Boylston Street in Boston. The ceremony was held for those ... more

The family of 2013 Boston Marathon bombing victim Martin Richard, from left, mother Denise, brother Henry, and father Bill Richard, place their hands over their hearts as they stand with former Boston Mayor Tom Menino, right, during a tribute in honor of the one year anniversary of the Boston Marathon bombings, Tuesday, April 15, 2014 in Boston. At left is a Mass. State Trooper. (AP Photo/Charles Krupa) ORG XMIT: MACK115 less

The family of 2013 Boston Marathon bombing victim Martin Richard, from left, mother Denise, brother Henry, and father Bill Richard, place their hands over their hearts as they stand with former Boston Mayor Tom ... more

Family members, survivors and friends of the 2013 Boston Marathon bombing react near the finish line after a remembrance ceremony on Boylston Street in Boston, Tuesday, April 15, 2014. (AP Photo/Elise Amendola) ORG XMIT: MAEA104 less

Family members, survivors and friends of the 2013 Boston Marathon bombing react near the finish line after a remembrance ceremony on Boylston Street in Boston, Tuesday, April 15, 2014. (AP Photo/Elise Amendola) ... more

Photo: Elise Amendola

Family members, survivors and friends of the 2013 Boston Marathon... Photo-6171545.83992 - Times Union

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Marathon survivor Erika Brannock, a teacher from Maryland, uses a walker as she prepares to cross the finish line following a tribute in honor of the one year anniversary of the Boston Marathon bombings, Tuesday, April 15, 2014 in Boston. (AP Photo/Charles Krupa) ORG XMIT: MACK108 less

Marathon survivor Erika Brannock, a teacher from Maryland, uses a walker as she prepares to cross the finish line following a tribute in honor of the one year anniversary of the Boston Marathon bombings, ... more

The family of 2013 Boston Marathon bombing victim Martin Richard, from left, mother Denise, brother Henry, and father Bill Richard walk onto Boylston street for the raising of the flag during a tribute on the one year anniversary of the Boston Marathon bombings, Tuesday, April 15, 2014 in Boston. (AP Photo/Charles Krupa) ORG XMIT: MACK106 less

The family of 2013 Boston Marathon bombing victim Martin Richard, from left, mother Denise, brother Henry, and father Bill Richard walk onto Boylston street for the raising of the flag during a tribute on the ... more

Former Boston Mayor Tom Menino, Boston Mayor Martin Walsh, Vice President Joe Biden and Mass. Gov. Deval Patrick lower their heads for a moment of silence during a tribute in honor of the one year anniversary of the Boston Marathon bombings, Tuesday, April 15, 2014 in Boston. (AP Photo/Charles Krupa) ORG XMIT: MACK105 less

Former Boston Mayor Tom Menino, Boston Mayor Martin Walsh, Vice President Joe Biden and Mass. Gov. Deval Patrick lower their heads for a moment of silence during a tribute in honor of the one year anniversary ... more

Police salute as a U.S. flag is raised at the finish line during a tribute in honor of the one year anniversary of the Boston Marathon bombings, Tuesday, April 15, 2014 in Boston. (AP Photo/Charles Krupa) ORG XMIT: MACK107 less

Police salute as a U.S. flag is raised at the finish line during a tribute in honor of the one year anniversary of the Boston Marathon bombings, Tuesday, April 15, 2014 in Boston. (AP Photo/Charles Krupa) ORG ... more

Photo: Charles Krupa

Police salute as a U.S. flag is raised at the finish line during a... Photo-6171549.83992 - Times Union

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The 2013 Boston Marathon bombing survivor Erika Brannock, a pre-school teacher from the Baltimore area, second from right, is hugged as her mom, Carol Downing, watches at right after a remembrance ceremony at the Marathon finish line on Boylston Street in Boston, Tuesday, April 15, 2014. (AP Photo/Elise Amendola) ORG XMIT: MAEA103 less

The 2013 Boston Marathon bombing survivor Erika Brannock, a pre-school teacher from the Baltimore area, second from right, is hugged as her mom, Carol Downing, watches at right after a remembrance ceremony at ... more

BOSTON, MA - APRIL 15: Boston area police and fire department flag bearers cross the finish line following the flag raising ceremony commemorating the one-year anniversary of the Boston Marathon bombings on Boylston Street near the finish line on April 15, 2014 in Boston, Massachusetts. Last year, two pressure cooker bombs killed three and injured an estimated 264 others during the Boston marathon, on April 15, 2013. (Photo by Jared Wickerham/Getty Images) ORG XMIT: 485055841 less

BOSTON, MA - APRIL 15: Boston area police and fire department flag bearers cross the finish line following the flag raising ceremony commemorating the one-year anniversary of the Boston Marathon bombings on ... more

Former Boston Mayor Thomas Menino, left, Boston Mayor Marty Walsh, center, and Vice President Joe Biden bow their heads along with the family of Boston Marathon bombing victim Martin Richard, behind, during a remembrance ceremony at the finish line on Boylston Street in Boston, Tuesday, April 15, 2014. (AP Photo/Elise Amendola) ORG XMIT: MAEA107 less

Former Boston Mayor Thomas Menino, left, Boston Mayor Marty Walsh, center, and Vice President Joe Biden bow their heads along with the family of Boston Marathon bombing victim Martin Richard, behind, during a ... more

2013 Boston Marathon bombing survivor Erika Brannock, a pre-school teacher from the Baltimore area, and her mother, Carol Downing, at right, walk across the Marathon finish line after a remembrance ceremony on Boylston Street in Boston, Tuesday, April 15, 2014. (AP Photo/Elise Amendola) ORG XMIT: MAEA109 less

2013 Boston Marathon bombing survivor Erika Brannock, a pre-school teacher from the Baltimore area, and her mother, Carol Downing, at right, walk across the Marathon finish line after a remembrance ceremony on ... more

BOSTON, MA - APRIL 15: Boston area police and fire department flag bearers get into formation during the flag raising ceremony commemorating the one-year anniversary of the Boston Marathon bombings on Boylston Street near the finish line on April 15, 2014 in Boston, Massachusetts. Last year, two pressure cooker bombs killed three and injured an estimated 264 others during the Boston marathon, on April 15, 2013. (Photo by Jared Wickerham/Getty Images) ORG XMIT: 485055841 less

BOSTON, MA - APRIL 15: Boston area police and fire department flag bearers get into formation during the flag raising ceremony commemorating the one-year anniversary of the Boston Marathon bombings on Boylston ... more

BOSTON, MA - APRIL 15: Boston area police and fire department flag bearers get into formation near the finish line during the flag raising ceremony commemorating the one-year anniversary of the Boston Marathon bombings on Boylston Street near the finish line on April 15, 2014 in Boston, Massachusetts. Last year, two pressure cooker bombs killed three and injured an estimated 264 others during the Boston marathon, on April 15, 2013. (Photo by Jared Wickerham/Getty Images) ORG XMIT: 485055841 less

BOSTON, MA - APRIL 15: Boston area police and fire department flag bearers get into formation near the finish line during the flag raising ceremony commemorating the one-year anniversary of the Boston Marathon ... more

Members of the Boston Red Sox stand for a moment of silence for the victims of the Boston Marathon bombings, befor ethe Red Sox's baseball game against the Chicago White Sox on Tuesday, April 15, 2014, in Chicago. (AP Photo/Charles Rex Arbogast) ORG XMIT: CXS103 less

Members of the Boston Red Sox stand for a moment of silence for the victims of the Boston Marathon bombings, befor ethe Red Sox's baseball game against the Chicago White Sox on Tuesday, April 15, 2014, in ... more

Photo: Charles Rex Arbogast, AP

Members of the Boston Red Sox stand for a moment of silence for the... Photo-6173450.83992 - Times Union

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BOSTON, MA - APRIL 15: Kids wave their American flags at the start of a candlelight vigil for the one-year anniversary of the Boston Marathon bombings at Garvey Park on April 15, 2014 in Boston, Massachusetts. Last year, two pressure cooker bombs killed three and injured an estimated 264 others during the Boston marathon, on April 15, 2013. (Photo by Jared Wickerham/Getty Images) ORG XMIT: 485055841 less

BOSTON, MA - APRIL 15: Kids wave their American flags at the start of a candlelight vigil for the one-year anniversary of the Boston Marathon bombings at Garvey Park on April 15, 2014 in Boston, Massachusetts. ... more

Photo: Jared Wickerham, Getty

BOSTON, MA - APRIL 15: Kids wave their American flags at the start... Photo-6173454.83992 - Times Union

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BOSTON, MA - APRIL 15: Two Dorchester residents light their candles during the candlelight vigil for the one-year anniversary of the Boston Marathon bombings at Garvey Park on April 15, 2014 in Boston, Massachusetts. Last year, two pressure cooker bombs killed three and injured an estimated 264 others during the Boston marathon, on April 15, 2013. (Photo by Jared Wickerham/Getty Images) ORG XMIT: 485055841 less

BOSTON, MA - APRIL 15: Two Dorchester residents light their candles during the candlelight vigil for the one-year anniversary of the Boston Marathon bombings at Garvey Park on April 15, 2014 in Boston, ... more

BOSTON, MA - APRIL 15: Two young girls light each others candles during a candlelight vigil for the one-year anniversary of the Boston Marathon bombings at Garvey Park on April 15, 2014 in Boston, Massachusetts. Last year, two pressure cooker bombs killed three and injured an estimated 264 others during the Boston marathon, on April 15, 2013. (Photo by Jared Wickerham/Getty Images) ORG XMIT: 485055841 less

BOSTON, MA - APRIL 15: Two young girls light each others candles during a candlelight vigil for the one-year anniversary of the Boston Marathon bombings at Garvey Park on April 15, 2014 in Boston, ... more

Photo: Jared Wickerham, Getty

BOSTON, MA - APRIL 15: Two young girls light each others candles... Photo-6173460.83992 - Times Union

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Heather McDade of Boston, center, reacts while watching a tribute ceremony with others on an over-sized outdoor monitor, Tuesday, April 15, 2014, on Boylston Street in Boston. The ceremony was held for those killed and injured in the bombings at the finish line of the Boston Marathon a year ago. (AP Photo/Steven Senne) ORG XMIT: MASR102 less

Heather McDade of Boston, center, reacts while watching a tribute ceremony with others on an over-sized outdoor monitor, Tuesday, April 15, 2014, on Boylston Street in Boston. The ceremony was held for those ... more

A Boston police officer pauses on the finish line during a tribute in honor of the one year anniversary of the Boston Marathon bombings, Tuesday, April 15, 2014 in Boston. (AP Photo/Charles Krupa) ORG XMIT: MACK112 less

A Boston police officer pauses on the finish line during a tribute in honor of the one year anniversary of the Boston Marathon bombings, Tuesday, April 15, 2014 in Boston. (AP Photo/Charles Krupa) ORG XMIT: ... more

Photo: Charles Krupa, AP

A Boston police officer pauses on the finish line during a tribute... Photo-6173474.83992 - Times Union

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2013 Boston Marathon bombing survivor Erika Brannock, a pre-school teacher from the Baltimore area, and her mother, Carol Downing, at right, walk across the Marathon finish line after a remembrance ceremony on Boylston Street in Boston, Tuesday, April 15, 2014. (AP Photo/Elise Amendola) ORG XMIT: MAEA109 less

2013 Boston Marathon bombing survivor Erika Brannock, a pre-school teacher from the Baltimore area, and her mother, Carol Downing, at right, walk across the Marathon finish line after a remembrance ceremony on ... more

Alex Fusco, of North Reading, Mass., right, hugs his mother Ernestine Fusco, center, at the conclusion of tribute ceremonies near the finish line of the Boston Marathon, Tuesday, April 15, 2014, in Boston. Alex, who was working as an athletic trainer near the finish line April 15, 2013, was among first responders to the scene of the bombing. (AP Photo/Steven Senne) ORG XMIT: MASR108 less

Alex Fusco, of North Reading, Mass., right, hugs his mother Ernestine Fusco, center, at the conclusion of tribute ceremonies near the finish line of the Boston Marathon, Tuesday, April 15, 2014, in Boston. ... more

BOSTON, MA - APRIL 15: Boston area police and fire department flag bearers cross the finish line following the flag raising ceremony commemorating the one-year anniversary of the Boston Marathon bombings on Boylston Street near the finish line on April 15, 2014 in Boston, Massachusetts. Last year, two pressure cooker bombs killed three and injured an estimated 264 others during the Boston marathon, on April 15, 2013. (Photo by Jared Wickerham/Getty Images) ORG XMIT: 485055841 less

BOSTON, MA - APRIL 15: Boston area police and fire department flag bearers cross the finish line following the flag raising ceremony commemorating the one-year anniversary of the Boston Marathon bombings on ... more

The family of 2013 Boston Marathon bombing victim Martin Richard, from left, mother Denise, brother Henry, and father Bill Richard, place their hands over their hearts as they stand with former Boston Mayor Tom Menino, right, during a tribute in honor of the one year anniversary of the Boston Marathon bombings, Tuesday, April 15, 2014 in Boston. At left is a Mass. State Trooper. (AP Photo/Charles Krupa) ORG XMIT: MACK115 less

The family of 2013 Boston Marathon bombing victim Martin Richard, from left, mother Denise, brother Henry, and father Bill Richard, place their hands over their hearts as they stand with former Boston Mayor Tom ... more

Former Boston Mayor Thomas Menino, left, Boston Mayor Marty Walsh, center, and Vice President Joe Biden bow their heads along with the family of Boston Marathon bombing victim Martin Richard, behind, during a remembrance ceremony at the finish line on Boylston Street in Boston, Tuesday, April 15, 2014. (AP Photo/Elise Amendola) ORG XMIT: MAEA107 less

Former Boston Mayor Thomas Menino, left, Boston Mayor Marty Walsh, center, and Vice President Joe Biden bow their heads along with the family of Boston Marathon bombing victim Martin Richard, behind, during a ... more

2013 Boston Marathon bombing survivor Erika Brannock, in hat, a pre-school teacher from the Baltimore area, is embraced as she walks across the Marathon finish line after a remembrance ceremony on Boylston Street in Boston, Tuesday, April 15, 2014. (AP Photo/Elise Amendola) ORG XMIT: MAEA110 less

2013 Boston Marathon bombing survivor Erika Brannock, in hat, a pre-school teacher from the Baltimore area, is embraced as she walks across the Marathon finish line after a remembrance ceremony on Boylston ... more

BOSTON, MA - APRIL 15: Tim Sorbanelli, 21, a Berklee College of Music student, plays his guitar near the finish line of the Boston Marathon prior to the flag raising ceremony commemorating the one-year anniversary of the Boston Marathon bombings on Boylston Street near the finish line on April 15, 2014 in Boston, Massachusetts. (Photo by Jared Wickerham/Getty Images) ORG XMIT: 485055841 less

BOSTON, MA - APRIL 15: Tim Sorbanelli, 21, a Berklee College of Music student, plays his guitar near the finish line of the Boston Marathon prior to the flag raising ceremony commemorating the one-year ... more

A note that says "No more hurting people. peace." hangs from a peace sign made from pipe cleaners near the scene of the second bomb blast on the one-year anniversary of the Boston Marathon bombings in Boston, April 15, 2014. The city paused Tuesday to honor those who had been killed and wounded and to demonstrate its defiance and resilience in the face of the attack. (Gretchen Ertl/The New York Times) ORG XMIT: XNYT19 less

A note that says "No more hurting people. peace." hangs from a peace sign made from pipe cleaners near the scene of the second bomb blast on the one-year anniversary of the Boston Marathon bombings in Boston, ... more

BOSTON, MA - APRIL 15: Tom Duggan hugs Sarah Rogo, who said they were both present last year at the marathon, while a billboard television screen broadcasts the ceremony commemorating the one year anniversary of the 2013 Boston Marathon Bombing , on April 15, 2014 in Boston, Massachusetts. Last year, two pressure cooker bombs killed three and injured an estimated 264 others during the Boston marathon, on April 15, 2013. Neary says she was standing near the site of the bombing before it went off. (Photo by Andrew Burton/Getty Images) ORG XMIT: 485055841 less

BOSTON, MA - APRIL 15: Tom Duggan hugs Sarah Rogo, who said they were both present last year at the marathon, while a billboard television screen broadcasts the ceremony commemorating the one year anniversary ... more

BOSTON, MA - APRIL 15: A woman pauses while observing the site of the second explosion after the ceremony commemorating the one year anniversary of the 2013 Boston Marathon Bombing, on April 15, 2014 in Boston, Massachusetts. Last year, two pressure cooker bombs killed three and injured an estimated 264 others during the Boston marathon, on April 15, 2013. Neary says she was standing near the site of the bombing before it went off. (Photo by Andrew Burton/Getty Images) ORG XMIT: 485055841 less

BOSTON, MA - APRIL 15: A woman pauses while observing the site of the second explosion after the ceremony commemorating the one year anniversary of the 2013 Boston Marathon Bombing, on April 15, 2014 in ... more

Photo: Andrew Burton, Getty

BOSTON, MA - APRIL 15: A woman pauses while observing the site of... Photo-6173499.83992 - Times Union

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A member of the bomb squad inspects an object after a controlled detonation at the finish line of the Boston Marathon in Boston, Tuesday, April 15, 2014. Police have blown up two unattended backpacks found near the Boston Marathon's finish line on Tuesday. They say they've taken a man into custody in connection with them. (AP Photo/Michael Dwyer) ORG XMIT: MAMD101 less

A member of the bomb squad inspects an object after a controlled detonation at the finish line of the Boston Marathon in Boston, Tuesday, April 15, 2014. Police have blown up two unattended backpacks found near ... more

Photo: Michael Dwyer, AP

A member of the bomb squad inspects an object after a controlled... Photo-6173446.83992 - Times Union